A system is known that uses a camera to monitor, on behalf of a healthcare professional such as a nurse or a caregiver, the behavior of, for example, a patient or a care recipient lying on a bed upon waking up or getting out of bed, and what he/she is doing on a bed. For example, in a medical institution, when behavior upon waking up or getting out of bed that may lead to a slip or fall accident occurs, or when unusual behavior in which the patient is suffering in a state in which he/she is not able to push a nurse call button occurs, it is effective if the system reports to a nurse on behalf of the patient.
In such a system, when the behavior of a person on a bed is recognized from an image captured by a camera, information about a bed area in the image is used as a reference. A technology is also known that arranges a plurality of markers at one side of a bed so as to recognize a position of the bed and a bed area by use of a three-dimensional position of a marker that is obtained from a distance image, and by use of a known size of the bed (see, for example, Patent Document 1).
Patent Document 1: Japanese Laid-open Patent Publication No. 2013-078433